Handle missing TargetFramework in nomination (#7196)

Author: nkolev92

src/NuGet.Clients/NuGet.SolutionRestoreManager/VSNominationUtilities.cs

@@ -158,7 +158,7 @@ internal static TargetFrameworkInformation ToTargetFrameworkInformation(
                 FrameworkReferences = frameworkReferences,
                 Imports = imports,
                 RuntimeIdentifierGraphPath = GetPropertyValueOrNull(targetFrameworkInfo.Properties, ProjectBuildProperties.RuntimeIdentifierGraphPath),
-                TargetAlias = GetPropertyValueOrNull(targetFrameworkInfo.Properties, ProjectBuildProperties.TargetFramework),
+                TargetAlias = GetPropertyValueOrNull(targetFrameworkInfo.Properties, ProjectBuildProperties.TargetFramework) ?? string.Empty,
                 Warn = warn,
                 PackagesToPrune = packagesToPrune,
             };
@@ -191,7 +191,7 @@ internal static ProjectRestoreMetadataFrameworkInfo ToProjectRestoreMetadataFram
             var tfi = new ProjectRestoreMetadataFrameworkInfo
             {
                 FrameworkName = GetTargetFramework(targetFrameworkInfo.Properties, projectFullPath),
-                TargetAlias = GetPropertyValueOrNull(targetFrameworkInfo.Properties, ProjectBuildProperties.TargetFramework)
+                TargetAlias = GetPropertyValueOrNull(targetFrameworkInfo.Properties, ProjectBuildProperties.TargetFramework) ?? string.Empty,
             };
 
             if (targetFrameworkInfo.Items?.TryGetValue(ProjectItems.ProjectReference, out var projectReferences) ?? false)

test/NuGet.Clients.Tests/NuGet.SolutionRestoreManager.Test/TestProjectRestoreInfoBuilder.cs

@@ -14,6 +14,7 @@ internal class TestProjectRestoreInfoBuilder
 {
     List<IVsTargetFrameworkInfo4> _targetFrameworks = new();
     List<VsReferenceItem2>? _toolReferences = null;
+    bool _useTargetFrameworks;
 
     public IVsProjectRestoreInfo3 Build()
     {
@@ -22,7 +23,7 @@ public IVsProjectRestoreInfo3 Build()
             throw new InvalidOperationException("At least one target framework must be added before building the project restore info.");
         }
 
-        var originalTargetFrameworks = string.Join(";", _targetFrameworks.Select(tf => tf.Properties[ProjectBuildProperties.TargetFramework]));
+        var originalTargetFrameworks = (_useTargetFrameworks || _targetFrameworks.Count > 1) ? string.Join(";", _targetFrameworks.Select(tf => tf.Properties[ProjectBuildProperties.TargetFramework])) : null;
 
         var pri = new VsProjectRestoreInfo3
         {
@@ -34,6 +35,11 @@ public IVsProjectRestoreInfo3 Build()
         return pri;
     }
 
+    public void WithTargetFrameworksProperty()
+    {
+        _useTargetFrameworks = true;
+    }
+
     public TestProjectRestoreInfoBuilder WithTargetFrameworkInfo(
         string targetFramework,
         Action<TargetFrameworkBuilder>? builder = null)
@@ -118,7 +124,7 @@ internal class TargetFrameworkBuilder
 
         public TargetFrameworkBuilder WithProperty(string key, string value)
         {
-            if (string.IsNullOrEmpty(key))
+            if (string.IsNullOrEmpty(value))
             {
                 Properties.Remove(key);
             }

test/NuGet.Clients.Tests/NuGet.SolutionRestoreManager.Test/VsSolutionRestoreServiceTests.cs

@@ -255,6 +255,7 @@ public async Task NominateProjectAsync_CrossTargeting(string targetFrameworks)
             {
                 builder.WithTargetFrameworkInfo(targetFramework);
             }
+            builder.WithTargetFrameworksProperty();
 
             var projectRestoreInfo = builder.Build();
 
@@ -1821,6 +1822,93 @@ public void ToPackageSpec_WithPrunePackageReference_AccountsForDefaults()
             resultB.Value.VersionRange.Should().Be(VersionRange.Parse("(, 1.0.0]"));
         }
 
+        [Fact]
+        public async Task NominateProjectAsync_SimulatedCPPProject_WithMissingTargetFramework_AliasRemainsEmpty()
+        {
+            var projectRestoreInfo = new TestProjectRestoreInfoBuilder()
+                .WithTargetFrameworkInfo(CommonFrameworks.Native.GetShortFolderName(), builder =>
+                {
+                    builder
+                    .WithProperty(ProjectBuildProperties.MSBuildProjectExtensionsPath, @"y:\src\some\project\obj")
+                    .WithProperty("MSBuildProjectFullPath", @"y:\src\some\project\project.vcxproj")
+                    .WithProperty("TargetFrameworkIdentifier", "NETFramework")
+                    .WithProperty("TargetFrameworkMoniker", ".NETFramework,Version=v4.8")
+                    .WithProperty("UsingMicrosoftNETSdk", "false")
+                    .WithProperty("TargetFramework", null!);
+                })
+                .Build();
+            // Act
+            var actualRestoreSpec = await CaptureNominateResultAsync(projectRestoreInfo);
+
+            // Assert
+            SpecValidationUtility.ValidateDependencySpec(actualRestoreSpec);
+
+            var actualProjectSpec = actualRestoreSpec.Projects.Single();
+            Assert.Equal("1.0.0", actualProjectSpec.Version.ToString());
+
+            var actualMetadata = actualProjectSpec.RestoreMetadata;
+            Assert.NotNull(actualMetadata);
+            Assert.Equal(ProjectStyle.PackageReference, actualMetadata.ProjectStyle);
+
+            Assert.Single(actualProjectSpec.TargetFrameworks);
+            var actualTfi = actualProjectSpec.TargetFrameworks.Single();
+
+            var expectedFramework = CommonFrameworks.Native;
+            Assert.Equal(expectedFramework, actualTfi.FrameworkName);
+            Assert.Equal(string.Empty, actualTfi.TargetAlias);
+
+            Assert.Single(actualProjectSpec.RestoreMetadata.TargetFrameworks);
+            var actualPRMFI = actualProjectSpec.RestoreMetadata.TargetFrameworks.Single();
+            Assert.Equal(expectedFramework, actualPRMFI.FrameworkName);
+            Assert.Equal(string.Empty, actualPRMFI.TargetAlias);
+        }
+
+        [Fact]
+        public async Task NominateProjectAsync_SimulatedCPPProject_WithMissingTargetFrameworkAndAssetTargetFallback_AliasRemainsEmpty()
+        {
+            var projectRestoreInfo = new TestProjectRestoreInfoBuilder()
+                .WithTargetFrameworkInfo(CommonFrameworks.Native.GetShortFolderName(), builder =>
+                {
+                    builder
+                    .WithProperty(ProjectBuildProperties.MSBuildProjectExtensionsPath, @"y:\src\some\project\obj")
+                    .WithProperty("MSBuildProjectFullPath", @"y:\src\some\project\project.vcxproj")
+                    .WithProperty("TargetFrameworkIdentifier", "NETFramework")
+                    .WithProperty("TargetFrameworkMoniker", ".NETFramework,Version=v4.8")
+                    .WithProperty("UsingMicrosoftNETSdk", "false")
+                    .WithProperty("TargetFramework", null!)
+                    .WithProperty("AssetTargetFallback", "net48");
+                })
+                .Build();
+            // Act
+            var actualRestoreSpec = await CaptureNominateResultAsync(projectRestoreInfo);
+
+            // Assert
+            SpecValidationUtility.ValidateDependencySpec(actualRestoreSpec);
+
+            var actualProjectSpec = actualRestoreSpec.Projects.Single();
+            Assert.Equal("1.0.0", actualProjectSpec.Version.ToString());
+
+            var actualMetadata = actualProjectSpec.RestoreMetadata;
+            Assert.NotNull(actualMetadata);
+            Assert.Equal(ProjectStyle.PackageReference, actualMetadata.ProjectStyle);
+
+            Assert.Single(actualProjectSpec.TargetFrameworks);
+            var actualTfi = actualProjectSpec.TargetFrameworks.Single();
+
+            var expectedFramework = CommonFrameworks.Native;
+            Assert.Equal(expectedFramework, actualTfi.FrameworkName);
+            Assert.Equal(string.Empty, actualTfi.TargetAlias);
+            Assert.IsType<AssetTargetFallbackFramework>(actualTfi.FrameworkName);
+            var assetTargetFallback = (AssetTargetFallbackFramework)actualTfi.FrameworkName;
+            Assert.Equal(expectedFramework, assetTargetFallback.RootFramework);
+            Assert.Equal([CommonFrameworks.Net48], assetTargetFallback.Fallback);
+
+            Assert.Single(actualProjectSpec.RestoreMetadata.TargetFrameworks);
+            var actualPRMFI = actualProjectSpec.RestoreMetadata.TargetFrameworks.Single();
+            Assert.Equal(expectedFramework, actualPRMFI.FrameworkName);
+            Assert.Equal(string.Empty, actualPRMFI.TargetAlias);
+        }
+
         private async Task<DependencyGraphSpec> CaptureNominateResultAsync(
             IVsProjectRestoreInfo3 pri,
             Mock<IProjectSystemCache>? cache = null)